Apparatus for reproducing images, and in particular, apparatus for the direct reproduction of images by utilizing a light sensitive element, a developer powder and an electric field has been known in the past. In the aforementioned apparatus, light rays are transmitted through an image copy and pass through a glass plate having a conductive coating thereon. The resistance of a photoconductive element adjacent the conductive coating becomes reduced and charges the developer power lying upon the illuminated areas of the conductive coating. The electric field thereupon attracts the charged developer powder and the particles migrate from the conductive coating leaving a visible powder image thereon. The developer powder particles can be suspended in a liquid medium, as well as in air or a vacuum.
The size limitations of the prior art apparatus, the difficulty of removing undeposited particles between the plates, the relative complexity of the apparatus and the required viewing optics made it advantageous to consider aternatives.